OT: How life came to Earth

John Larkin hasn't heard of the RNA-based stage that had to precede DNA-based reproduction, and is still visible in the nuts and bolts of cellular processing. RNA does have the advantage that there are RNA-based "enzymes", so that long enough strings of RNA could have created the first self-replicating system.

It's easy to calculate probabilities for the wrong process. Finding the more probable process that might have happened is trickier.

They aren't because they just push back the problem to someplace even less accessible to us.

You just got carved up by Occam's Razor.

We have considered the possibilities rather more comprehensively than you have.

Sneering at your half-baked ideas does seem to be the appropriate response.

It eventually lead to us. It's a trifle egocentric to be impressed by that. The species that replaces us may find something else to get impressed by. It's possible that we may have come up with a new trick that may give us access to a wider range of habitats than any previous life-form and we may evolve to exploit them. It's just as likely that we've found a blind alley in that the skills that might let us exploit new habitats are perfectly capable of destroying the only one that supports us at the moment.

DNA didn't have to evolve on it's own. It seems likely that RNA based life preceded that - and there are enough RNA-based components in life as we know it to suggest that DNA was to RNA what hard drives are to floppies. Both exist to encode and generate proteins, so seeing the proteins as the starting point does have it's attractions. The fact that some RNA strings can work as enzymes takes the gilt off that particular bit of gingerbread.

Or not yet.

And the SETI project exists to check them out. There's no data available yet that makes it a useful hypothesis.

This is the kind of response Flyguy would have come up with, based on wishful thinking rather an any intelligent consideration of what had been said.

John Larkin has earned the sneering he has got, and - unlike Flyguy - he probably isn't too dim to realise it. He *is* too vain to admit it.

Nonsense. I'm considering the virtues of theories according to normal scientific-theory assesment protocols. It isn't theologically 'good' that concerns a scientist, though that was tried out (alchemy spent a lot of effort on old-testament Egyptian lore).

No theory is 'good' if it can't be explored or used. Life-was-planted doesn't even offer blind alleys, let alone roads to understanding.

Not a bit. But "The Science" of both is incomplete. There remains room for discovery.

Of course they do, at least to me. But the anti-creationist concensus seems to blur the boundary, that abiogenesis was itself gradual chemical evolution, which I consider to be absurd.

"Although the occurrence of abiogenesis is uncontroversial among scientists, its possible mechanisms are poorly understood."

How can something that's un-observed and not understood be uncontroversial? The answer is that concensus crushes thinking.

I seem to believe in evolution more than you do.

I was making two points. One is that your statement "the purpose of nucleic acids is as a blueprint for proteins" is a massive over-simplification. The other is that it is entirely plausible that RNA (or similar nucleic acids) were the basis for life before proteins were involved, at least as far as we currently know. More research into these areas may eliminate or strengthen the hypothesis.

Sure. /All/ hypothesis for abiogenesis are based on improbable coincidence. But that's okay - a small probability multiplied by countless mudpools or volcanic vents (or other appropriate environment) across the earth, multiplied by hundreds of millions of years, add up to a reasonable probability in total.

Indeed. We can speculate, and we can find different ways to estimate conditions on the early earth, and we can experiment to replicate these and see if we can eliminate some possibilities and promote others. In experiments and simulations, pretty much all the parts of abiogenesis have been shown - formation of cell membranes, protein fabrication, metabolism, replication, nucleic acids, etc. The big challenge is finding out how all (or at least most) of these parts could have formed in the same environment.

Basic proteins can form and have simple function without nucleic acids. Basic nucleic acids can form and have simple function without proteins. There is, currently, no way to know which was first. Perhaps both orderings are feasible - or perhaps life required both to have formed coincidentally in the same place and time.

Yes.

There is also the big issue that on a cosmic scale, planets are unstable.

So far, we have only one planet with life to look at. We can make guesses from that, but of course we have no way of knowing the accuracy of our extrapolations. With that proviso, we know:

1. Life on earth formed pretty much as soon as conditions were tolerable. Within a few hundred million years of there being surface water, an atmosphere (giving more stable global temperature) and an end to the planet-building phase of the solar system, life evolved on earth.

1. It took about 2 billion years to go from simple cellular lifeforms (bacteria and archaea) to the next big thing - the eukaryote.

2. It took a hundred million years to invent sex, then development really started taking off. A few more hundred million years, and multi-cellular life was common.

1. Life tends to stabilise and find a balance, with long periods of relatively little change. This is interspersed with catastrophes that lead to mass extinctions, followed by rapid evolutionary diversity to fill the niches that open up once conditions improve again.

2. "Advanced" animal life is only a few hundred million years old. "Intelligent" life is far younger.

This would all suggest that its relatively easy for basic lifeforms to form and evolve on planets with the appropriate fundamental requirements (liquid water, stable environments, appropriate chemicals). But evolution of complex and then intelligent life requires a lot more time, and a lot more luck with disasters that are almost but not quite deadly to the planet - "whatever doesn't kill you makes you stronger".

What are the chances of a planet in this galaxy surviving for 4.5 billion years without being hit by a nearby gamma glint, bumped a little out of orbit by a passing star, getting hit by a meteor a few times bigger than the dinosaurs' bane? I haven't seen the calculations, but I suspect that very few planets remain viable for life for long enough without the universe obliterating their populations - that's before they get intelligent enough to do it themselves.

Science is /always/ incomplete. That's part of the point.

Merely claiming that you understand things does not make it true - your ignorance shines through in your posts. There is no more evidence to your understanding than there is evidence to your "ideas".

You love to complain when people quickly dismiss your baseless random thoughts, yet you dismiss serious science on the grounds that /you/ consider it to be absurd.

Right...

You really haven't given this much thought, have you? /Please/ tell me you haven't. The alternative is that you are incapable of simple rational thought.

This is just a simple two-step process.

We know that at some point in the past, there was no life. (Let's humour you and say we are talking about the planet that developed the lifeforms that made the robots that seeded the earth - for those that prefer to stick to reality, we are talking about the earth or any other planet that developed life itself.)

We know that there is life here now.

Therefore, the planet moved from the state of having no life to the state of having life, in a purely chemical and physical manner. That is termed "abiogenesis" - the formation of life from non-living matter.

Abiogenesis is completely uncontroversial. Even if you believe in alien robots, abiogenesis happened on /their/ planet.

Really, it's not hard.

(The only alternative is that some god or gods created life - and that is not science. Science can't disprove anything about gods, and there is no evidence of any gods. It is simply a non-issue as far as science is concerned, since if evidence of gods were found, that would then be science.)

$DEITY only knows what you believe in, or why.

Next you'll be telling us that the red sun of Krypton means that Superman's cells produce antigravity that lets him fly, and thus /you/ believe in gravity more than I do.

The more rational and scientifically minded among us don't rely on "belief" for evolution - we rely on knowledge of the best current theories in science, with the expectation that these will be changed if new evidence is found that contradicts them.

Then Science should be cautious about concensus and certainty, especially about things that are unexplained and not subject to repeatable experiment.

You claim to understand the origin of life. I speculate precisely because I don't understand it. Nobody does.

Design is speculating widely about unknowns. Uncertainty, confusion, wandering about the solution space are assets to design. Concensus, surity, convention, "good engineering practice" are the enemies of invention.

Design something, post it, and we can discuss it.

Design something. It's on-topic and requires rational thought.

Right. But maybe not DNA.

Us? That's funny. A clan of Science groupies.

New evidence? What's the old evidence for life springing from primordial soup and evolution in RNA World? Making a few organic molecules in a test tube, with an electric arc, ain't making a living, reproducing cell. It's not a chemistry problem, it's an information problem.

At the lowest level, it *is* a chemistry problem. The known fact is that polypeptides make copies of themselves under the right conditions. There is no need for complex proteins to do it, even if it works better with them. There is no need for this process to happen inside cells, although that does provide a better environment with the right conditions. The early details of the process, and the various steps towards increasing sophistication are still very uncertain, but the overall outline is pretty clear.

We can't exclude (yet) that life came from elsewhere, but even then, this solves nothing. It's just another level of indirection. It has to start somewhere. There may be life elsewhere, or not. We don't yet have the statistics to make any plausible guesses.

Jeroen Belleman

Some DNA-free bacteria probably still exist, but have not yet been found. But there are plenty of bacteria that have never been studied, so don't lose hope. They may be only in extreme environments, like near deep-sea "smoker" vents.

.

"Does a DNA-less cellular organism exist on Earth?", Akira Hiyoshi, Kohji Miyahara, Chiaki Kato, Yasumi Ohshima, Genes Cells, . 2011 Dec;16(12):1146-58. doi: 10.1111/j.1365-2443.2011.01558.x. Epub 2011 Nov 17.

Could well be underway, done by the same folk who have been trying to find the minimum number of genes a bacteria can have. I don't recall the current number, but it was something like a thousand. I laid out the details in the "cool book" thread of mid 2021, as I recall.

Joe Gwinn

Uncertain and pretty clear? RNA world is just as faith-based as life springing from the head of Zeus.

The dilemma with DNA *is* an information problem. What was the bootstrap process for an incredibly complex machine that is programmed to make itself?

Why do guesses have to be plausible? Seems like a very sterile way to live.

False. The 'caution' you refer to is a social concern, NOT a knowledge-and-understanding one, thus is not of primary interest in the sciences. The 'should be' phrase means you're trying to invoke some kind of value judgment, but whether this is true-false, good-evil, or some religious morality scale, is completely obscure.

Criticism of a science theory is easy: you suggest an improvement. You don't discard bits and invoke cancel-culture concepts to demonize... if you expect to be taken seriously.

John Larkin thinks he knows enough to make that claim. He clearly doesn't.

But not a lot of room for ill-informed speculation.

As if your opinion is worth posting

Life exists now. It wouldn't have existed at the instant of the Big Bang, so it had to have come into existence sometime later. It is observed now, so abiogenenis has has to have happened sometime and to that it extent it has been observed. Exactly how it happened is less obvious.

You seem to feel that it crushes your sort of "thinking". Sadly, it hasn't.

You may believe in something you imagine to be evolution, but you don't seem to know enough about what the word means to more sophisticated people for this to be a particularly meaningful claim. Or to put it more bluntly, your ideas about "evolution" are comically wide of the mark.

Science is a social system. It usually resists theories that upset the concensus. It's been observed that the old guard has to die out before new theories are taken seriously; that slows things down. Science is also notorious for rejecting theories and discoveries from women, which is hardly objective.

"A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it. . . . An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out, and that the growing generation is familiarized with the ideas from the beginning: another instance of the fact that the future lies with the youth.

— Max Planck, Scientific autobiography, 1950, p. 33, 97

Are you a scientist?

"Taken seriously" is part of the problem in science. My version of "taken seriously" is a purchase order.

Given that it's Venter, I would assume that it can reproduce. The actual scientific articles (versus an interview) will likely tell.

Joe Gwinn

M<snip>

It absolutely is. You don't know enough about the subject to appreciate precisely how this caution is baked into the scientific method.

He didn't. He laid out what we do know about it.

You speculate very imprecisely because you not only don't understand it , but also don't know enough about area to have any kind of remotely useful ideas.

But you don't seem to have invented anything patentable, and your approach to the design process seems to be remarkably slap-dash.

John Larkin plays what he imagines to be his "get out of jail for free" card.

He is asserting his usual claim that he is capable of design electronic design, which is suspect, and promises to discuss somebody else's design, which he never does.